This invention relates to a machine for processing meat pieces, namely for macerating and treating meat pieces or blocks such as cured ham, fresh meat or other meat products which in many cases have been previously injected with brine or other preserving or improving product, the processing of which comprises massaging actions by rubbing the meat pieces with each other and with the walls and alternatively strongly knocking them which are lifted for said purpose and left to fall from a certain height on the rest of the meat mass.
The machine involved is of the type which comprises a large drum of any suitable section, in general cylindric, which has a side wall, a closed rear end and an open front end, to supply the meat pieces which fill it up to about 40% its capacity, and for unloading them, said drum showing means for rotating in two directions, about its centerline, said axis being horizontally oriented during the step of treatment and being provided with a cover with tight closing means which have available a driving mechanical device. Preferably, said drum has integrated, surrounding its side wall, means such as a thermal conditioning sleeve which allow to carry out an adjustment of the meat mass temperature at will, during the step of maceration, as well as other means of access to the interior of the drum, to carry out alternative steps of vacuum and pressurized air or oxygen blowing (overpressure), of variable duration, within the drum, the consecutive states of vacuum and pressure very effectively aid to macerate the products, said drum being mechanically coupled with a motor which confers it a torque of rotation drive in one or the other direction, in the different periods of the treatment cycle.
In a conventional structure, said cylindric drum rests by its front part (which includes a tronco-conical portion which integrates the loading/unloading mouth) on rollers, mounted on a supporting structure, which are supported against a circumferential band of its side wall, and by its rear part the drum is coupled to means, linked to said structure, for its drive in rotation, guided, about a revolution axis, in both directions, the structure being hinged with respect to a bench and associated to means, such as fluid dynamic cylinders, to let it be tilted, so that said drum rotating motion can be carried out in different positions of said axis inclination.
In addition, said drum integrates on its internal face, a plurality of blades which define a series of oblong open receptacles, oriented as generatrices along the drum, said receptacles being filled with the meat, acting as spoons in one of the rotation directions, which provokes that the meat, during said step, is lifted and then let to fall by gravity on the rest of the meat mass which occupies the recess within the drum, from the higher part thereof, while in the opposite rotating direction, it slides on the inclined surface forming the external wall of said receptacles, being gently massaged. That is to say, during the treatment the action of a strong knocking the meat is matched with a gentle massage, all of it under conditions of temperature, pressure (cycles of vacuum and pressure) and internal environment of the chamber controlled at will.
Examples of this kind of machines appear disclosed in Spanish patents no 406,947 and 435,711, as well as in U.S. Pat. No. 4,791,705, all of them owned by the holder of this application of patent.
Other machines of the kind referred to are disclosed in Patents EP-A-0455611, SU-835973, WO-A-89/08982 and WO-A92/18011.
With respect to above background, the invention proposes a simplified supporting structure, reducing to the minimum the elements constituting it and its respective sections, the distribution of the loads having been optimized with respect to the structural supporting members as well when the drum rotates, with more or less brisk displacements of meat mass which generates unbalances in the whole of said drum, as in idle situation. When planning said supporting structure the steps of loading and unloading meat pieces with oblique drum inclinations and new displacement of the meat mass, to attenuate its effects have been analyzed. In addition, means for supporting and coupling the drum to said supporting structure have been provided which determine a minimization of the effects which tends to have a repercussion on the drum-bearing structure links, derived from possible eccentricities at the periphery of the drum (unavoidable because of its large diameter).
Otherwise, the driving means to produce the drum tilt are arranged with relation to said supporting structure so that a maximum profit of its performances is achieved.
Also the drum internal blades show a configuration which favours the macerating treatment explained and also facilitates an effective cleaning inside the drum.
Thus, said supporting structure is hinged on the front part of a bench or bottom constituted by a not very high substantially horizontal frame supported on the floor, on feet with means of elastic nature to absorb vibrations, so that hinged joints are defined with said bench, aligned according to a horizontal axis we shall call B close to the floor and orthogonal to the drum revolution axis, and at its rear part the structure is joined to a plate bearing the drum rotating motion driving and guiding means, said junction being carried out intercalating elastic elements, aligned according to an axis, designated as C, horizontal, orthogonal and secant or substantially close to said revolution axis A, behind the drum closed end, and there exists at each side of the drum a fluid dynamic cylinder lied by means of a first hinged joint to the rear part of said bench and by a second hinged Joint to the rear end of the structure at a point close to said axis C, said first hinged joint remaining aligned according to an horizontal axis D, close to the floor and orthogonal to said revolution axis A, the gap between the axis B and C being significantly larger that the gap between axis B and D, which allows that the cylinders adopt an inclined position, with which a best effectiveness thereof can be achieved with a shorter run of the stem of the fluid dynamic cylinder, with respect to that possible with another arrangement of mounting.
As for the drum blades, they are extended, regularity spaced, following a generatrix along a substantial portion of the internal face of the side wall of said drum and they are constituted by an asymmetric cross profile, inclined sideways, with a free, longitudinal, rounded edge delimited by flanks one of them forming a spoon-shaped recess and the other a slight pendent ramp. Said arrangement determines that said drum rotates in the direction said recess has at the front, the meat is catched by it and lifted up to the higher part of said drum, it falls again from said height to the bottom to start the new cycle, and when the drum rotates in the opposite direction, the meat pieces gently slide on said ramp and rounded edge, causing a massage friction between the meat pieces without lifting them.